Title: Re: [COUPERS-TECH] Nosewheel struts S/N 113-813
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It has been said that a man with a watch knows what time it is. A man with two watches is never sure.
In the same sense, there is obvious confusion (that I feel guilty of contributing to) in information posted this month regarding the correct fluid to use in early nose gear struts. I hope if there is authoritative information in conflict with (any of) that which follows, those so aware will bring it to the attention of our forum.
IN THE BEGINNING, there were 112 pre-war Ercoupes produced with the double- fork (Hayes, P/N 34003) fork and wheel (*P/N 34090-1). When production resumed in 1945, the decision was made to deplete then-existing stock of the pre-war gear before commencing production installation a revised nose gear.
Serials 113 thru 186 received the pre-war gear after which the revised gear (now called the "steel" gear) was installed to serial no. 4500. Per the Ercoupe Service Manual signed by "R. Sanders, Service Manager, on January 1, 1947, (but actually incorporating a reference in the rear to the First Model 415-D, Serial No. 4424, which was manufactured on 3/25/47), "struts prior to serial no. 813 (which still have natural rubber seals), use Lockheed or Delco brake fluid (vegetable oil base)." That made complete "service sense", as that fluid was also specified for servicing main landing gear oleos prior to serial no. 813.
Close examination of the exploded view of the old-style gear and associated parts list reveals only two flexible parts. The "Absorber-shock" in "current" Parts Manuals (P/N 34087) was the same part number called for in the older gear. The "Oil Seal" in "current" Parts Manuals (P/N 34126-1) and referred to as "Oil Retainer" in ESM-41 is different from the "Retainer-oil" (P/N 34082-1) in the earlier gear, so it would appear this single part was incompatible with the later AN-VV-O-366b (red) hydraulic fluid.
Above "Oil Seal" P/N 34126-1 and "Retainer-oil" P/N 34082-1 are interchangable per a Sanders Spare Parts Price List dated 1/15/54 which identifies it as being "effective Ercoupe serial numbers 1-4423" and does not show the earlier "natural rubber seal" as then being available. "Current" Parts Manuals call for (replacement) installation of the later P/N 34126-1 "Oil Seal" for Ercoupes serials 187-4500. We know the "Oil Retainer" was replaced in ESM-41 rework (referenced in the 1/1/47 Service Manual).
If any nose gear strut with the earlier "natural rubber seal" that requires servicing with vegetable oil remains in service, I would highly recomment compliance with ESM-41; forever thence to be serviced with AN-VV-O-366b (red) hydraulic fluid!
This should further clarify similar infomation contained in my TECH posting of 2/3/03 11:59am, although at that time I was clearly wrong in believing that aircraft nose gear fitted to serials 187-813 ORIGINALLY were fitted with an Oil Seal/Retainer compatible with AN-VV-O-366b hydraulic fluid. (Thanks, Lynn!)
Nobody promised easy...but I hope the above will simplify the proper servicing of any nose strut currently on early Ercoupes, serials 813 and below.
Regards,
William R. Bayne
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(copyright 2002)
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